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* fs: create and use seq_show_option for escapingKees Cook2015-10-131-3/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit a068acf2ee77693e0bf39d6e07139ba704f461c3 upstream. Many file systems that implement the show_options hook fail to correctly escape their output which could lead to unescaped characters (e.g. new lines) leaking into /proc/mounts and /proc/[pid]/mountinfo files. This could lead to confusion, spoofed entries (resulting in things like systemd issuing false d-bus "mount" notifications), and who knows what else. This looks like it would only be the root user stepping on themselves, but it's possible weird things could happen in containers or in other situations with delegated mount privileges. Here's an example using overlay with setuid fusermount trusting the contents of /proc/mounts (via the /etc/mtab symlink). Imagine the use of "sudo" is something more sneaky: $ BASE="ovl" $ MNT="$BASE/mnt" $ LOW="$BASE/lower" $ UP="$BASE/upper" $ WORK="$BASE/work/ 0 0 none /proc fuse.pwn user_id=1000" $ mkdir -p "$LOW" "$UP" "$WORK" $ sudo mount -t overlay -o "lowerdir=$LOW,upperdir=$UP,workdir=$WORK" none /mnt $ cat /proc/mounts none /root/ovl/mnt overlay rw,relatime,lowerdir=ovl/lower,upperdir=ovl/upper,workdir=ovl/work/ 0 0 none /proc fuse.pwn user_id=1000 0 0 $ fusermount -u /proc $ cat /proc/mounts cat: /proc/mounts: No such file or directory This fixes the problem by adding new seq_show_option and seq_show_option_n helpers, and updating the vulnerable show_option handlers to use them as needed. Some, like SELinux, need to be open coded due to unusual existing escape mechanisms. [akpm@linux-foundation.org: add lost chunk, per Kees] [keescook@chromium.org: seq_show_option should be using const parameters] Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Acked-by: Jan Kara <jack@suse.com> Acked-by: Paul Moore <paul@paul-moore.com> Cc: J. R. Okajima <hooanon05g@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 3.2: - Drop changes to overlayfs, reiserfs - Drop vers option from cifs - ceph changes are all in one file - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* perf: Fix fasync handling on inherited eventsPeter Zijlstra2015-10-131-2/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | commit fed66e2cdd4f127a43fd11b8d92a99bdd429528c upstream. Vince reported that the fasync signal stuff doesn't work proper for inherited events. So fix that. Installing fasync allocates memory and sets filp->f_flags |= FASYNC, which upon the demise of the file descriptor ensures the allocation is freed and state is updated. Now for perf, we can have the events stick around for a while after the original FD is dead because of references from child events. So we cannot copy the fasync pointer around. We can however consistently use the parent's fasync, as that will be updated. Reported-and-Tested-by: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho deMelo <acme@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: eranian@google.com Link: http://lkml.kernel.org/r/1434011521.1495.71.camel@twins Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* tracing/filter: Do not allow infix to exceed end of stringSteven Rostedt (Red Hat)2015-08-121-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 6b88f44e161b9ee2a803e5b2b1fbcf4e20e8b980 upstream. While debugging a WARN_ON() for filtering, I found that it is possible for the filter string to be referenced after its end. With the filter: # echo '>' > /sys/kernel/debug/events/ext4/ext4_truncate_exit/filter The filter_parse() function can call infix_get_op() which calls infix_advance() that updates the infix filter pointers for the cnt and tail without checking if the filter is already at the end, which will put the cnt to zero and the tail beyond the end. The loop then calls infix_next() that has ps->infix.cnt--; return ps->infix.string[ps->infix.tail++]; The cnt will now be below zero, and the tail that is returned is already passed the end of the filter string. So far the allocation of the filter string usually has some buffer that is zeroed out, but if the filter string is of the exact size of the allocated buffer there's no guarantee that the charater after the nul terminating character will be zero. Luckily, only root can write to the filter. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* tracing/filter: Do not WARN on operand count going below zeroSteven Rostedt (Red Hat)2015-08-121-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | commit b4875bbe7e68f139bd3383828ae8e994a0df6d28 upstream. When testing the fix for the trace filter, I could not come up with a scenario where the operand count goes below zero, so I added a WARN_ON_ONCE(cnt < 0) to the logic. But there is legitimate case that it can happen (although the filter would be wrong). # echo '>' > /sys/kernel/debug/events/ext4/ext4_truncate_exit/filter That is, a single operation without any operands will hit the path where the WARN_ON_ONCE() can trigger. Although this is harmless, and the filter is reported as a error. But instead of spitting out a warning to the kernel dmesg, just fail nicely and report it via the proper channels. Link: http://lkml.kernel.org/r/558C6082.90608@oracle.com Reported-by: Vince Weaver <vincent.weaver@maine.edu> Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* rcu: Correctly handle non-empty Tiny RCU callback list with none readyPaul E. McKenney2015-08-121-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | commit 6e91f8cb138625be96070b778d9ba71ce520ea7e upstream. If, at the time __rcu_process_callbacks() is invoked, there are callbacks in Tiny RCU's callback list, but none of them are ready to be invoked, the current list-management code will knit the non-ready callbacks out of the list. This can result in hangs and possibly worse. This commit therefore inserts a check for there being no callbacks that can be invoked immediately. This bug is unlikely to occur -- you have to get a new callback between the time rcu_sched_qs() or rcu_bh_qs() was called, but before we get to __rcu_process_callbacks(). It was detected by the addition of RCU-bh testing to rcutorture, which in turn was instigated by Iftekhar Ahmed's mutation testing. Although this bug was made much more likely by 915e8a4fe45e (rcu: Remove fastpath from __rcu_process_callbacks()), this did not cause the bug, but rather made it much more probable. That said, it takes more than 40 hours of rcutorture testing, on average, for this bug to appear, so this fix cannot be considered an emergency. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> [bwh: Backported to 3.2: adjust filename, context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* hrtimer: Allow concurrent hrtimer_start() for self restarting timersPeter Zijlstra2015-08-121-3/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 5de2755c8c8b3a6b8414870e2c284914a2b42e4d upstream. Because we drop cpu_base->lock around calling hrtimer::function, it is possible for hrtimer_start() to come in between and enqueue the timer. If hrtimer::function then returns HRTIMER_RESTART we'll hit the BUG_ON because HRTIMER_STATE_ENQUEUED will be set. Since the above is a perfectly valid scenario, remove the BUG_ON and make the enqueue_hrtimer() call conditional on the timer not being enqueued already. NOTE: in that concurrent scenario its entirely common for both sites to want to modify the hrtimer, since hrtimers don't provide serialization themselves be sure to provide some such that the hrtimer::function and the hrtimer_start() caller don't both try and fudge the expiration state at the same time. To that effect, add a WARN when someone tries to forward an already enqueued timer, the most common way to change the expiry of self restarting timers. Ideally we'd put the WARN in everything modifying the expiry but most of that is inlines and we don't need the bloat. Fixes: 2d44ae4d7135 ("hrtimer: clean up cpu->base locking tricks") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Ben Segall <bsegall@google.com> Cc: Roman Gushchin <klamm@yandex-team.ru> Cc: Paul Turner <pjt@google.com> Link: http://lkml.kernel.org/r/20150415113105.GT5029@twins.programming.kicks-ass.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.2: adjust filename, context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* Fix lockup related to stop_machine being stuck in __do_softirq.Ben Greear2015-08-071-3/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 34376a50fb1fa095b9d0636fa41ed2e73125f214 upstream. The stop machine logic can lock up if all but one of the migration threads make it through the disable-irq step and the one remaining thread gets stuck in __do_softirq. The reason __do_softirq can hang is that it has a bail-out based on jiffies timeout, but in the lockup case, jiffies itself is not incremented. To work around this, re-add the max_restart counter in __do_irq and stop processing irqs after 10 restarts. Thanks to Tejun Heo and Rusty Russell and others for helping me track this down. This was introduced in 3.9 by commit c10d73671ad3 ("softirq: reduce latencies"). It may be worth looking into ath9k to see if it has issues with its irq handler at a later date. The hang stack traces look something like this: ------------[ cut here ]------------ WARNING: at kernel/watchdog.c:245 watchdog_overflow_callback+0x9c/0xa7() Watchdog detected hard LOCKUP on cpu 2 Modules linked in: ath9k ath9k_common ath9k_hw ath mac80211 cfg80211 nfsv4 auth_rpcgss nfs fscache nf_nat_ipv4 nf_nat veth 8021q garp stp mrp llc pktgen lockd sunrpc] Pid: 23, comm: migration/2 Tainted: G C 3.9.4+ #11 Call Trace: <NMI> warn_slowpath_common+0x85/0x9f warn_slowpath_fmt+0x46/0x48 watchdog_overflow_callback+0x9c/0xa7 __perf_event_overflow+0x137/0x1cb perf_event_overflow+0x14/0x16 intel_pmu_handle_irq+0x2dc/0x359 perf_event_nmi_handler+0x19/0x1b nmi_handle+0x7f/0xc2 do_nmi+0xbc/0x304 end_repeat_nmi+0x1e/0x2e <<EOE>> cpu_stopper_thread+0xae/0x162 smpboot_thread_fn+0x258/0x260 kthread+0xc7/0xcf ret_from_fork+0x7c/0xb0 ---[ end trace 4947dfa9b0a4cec3 ]--- BUG: soft lockup - CPU#1 stuck for 22s! [migration/1:17] Modules linked in: ath9k ath9k_common ath9k_hw ath mac80211 cfg80211 nfsv4 auth_rpcgss nfs fscache nf_nat_ipv4 nf_nat veth 8021q garp stp mrp llc pktgen lockd sunrpc] irq event stamp: 835637905 hardirqs last enabled at (835637904): __do_softirq+0x9f/0x257 hardirqs last disabled at (835637905): apic_timer_interrupt+0x6d/0x80 softirqs last enabled at (5654720): __do_softirq+0x1ff/0x257 softirqs last disabled at (5654725): irq_exit+0x5f/0xbb CPU 1 Pid: 17, comm: migration/1 Tainted: G WC 3.9.4+ #11 To be filled by O.E.M. To be filled by O.E.M./To be filled by O.E.M. RIP: tasklet_hi_action+0xf0/0xf0 Process migration/1 Call Trace: <IRQ> __do_softirq+0x117/0x257 irq_exit+0x5f/0xbb smp_apic_timer_interrupt+0x8a/0x98 apic_timer_interrupt+0x72/0x80 <EOI> printk+0x4d/0x4f stop_machine_cpu_stop+0x22c/0x274 cpu_stopper_thread+0xae/0x162 smpboot_thread_fn+0x258/0x260 kthread+0xc7/0xcf ret_from_fork+0x7c/0xb0 Signed-off-by: Ben Greear <greearb@candelatech.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Pekka Riikonen <priikone@iki.fi> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Rui Xiang <rui.xiang@huawei.com>
* softirq: reduce latenciesEric Dumazet2015-08-071-8/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit c10d73671ad30f54692f7f69f0e09e75d3a8926a upstream. In various network workloads, __do_softirq() latencies can be up to 20 ms if HZ=1000, and 200 ms if HZ=100. This is because we iterate 10 times in the softirq dispatcher, and some actions can consume a lot of cycles. This patch changes the fallback to ksoftirqd condition to : - A time limit of 2 ms. - need_resched() being set on current task When one of this condition is met, we wakeup ksoftirqd for further softirq processing if we still have pending softirqs. Using need_resched() as the only condition can trigger RCU stalls, as we can keep BH disabled for too long. I ran several benchmarks and got no significant difference in throughput, but a very significant reduction of latencies (one order of magnitude) : In following bench, 200 antagonist "netperf -t TCP_RR" are started in background, using all available cpus. Then we start one "netperf -t TCP_RR", bound to the cpu handling the NIC IRQ (hard+soft) Before patch : # netperf -H 7.7.7.84 -t TCP_RR -T2,2 -- -k RT_LATENCY,MIN_LATENCY,MAX_LATENCY,P50_LATENCY,P90_LATENCY,P99_LATENCY,MEAN_LATENCY,STDDEV_LATENCY MIGRATED TCP REQUEST/RESPONSE TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 7.7.7.84 () port 0 AF_INET : first burst 0 : cpu bind RT_LATENCY=550110.424 MIN_LATENCY=146858 MAX_LATENCY=997109 P50_LATENCY=305000 P90_LATENCY=550000 P99_LATENCY=710000 MEAN_LATENCY=376989.12 STDDEV_LATENCY=184046.92 After patch : # netperf -H 7.7.7.84 -t TCP_RR -T2,2 -- -k RT_LATENCY,MIN_LATENCY,MAX_LATENCY,P50_LATENCY,P90_LATENCY,P99_LATENCY,MEAN_LATENCY,STDDEV_LATENCY MIGRATED TCP REQUEST/RESPONSE TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 7.7.7.84 () port 0 AF_INET : first burst 0 : cpu bind RT_LATENCY=40545.492 MIN_LATENCY=9834 MAX_LATENCY=78366 P50_LATENCY=33583 P90_LATENCY=59000 P99_LATENCY=69000 MEAN_LATENCY=38364.67 STDDEV_LATENCY=12865.26 Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: David Miller <davem@davemloft.net> Cc: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Rui Xiang <rui.xiang@huawei.com>
* __ptrace_may_access() should not deny sub-threadsMark Grondona2015-08-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | commit 73af963f9f3036dffed55c3a2898598186db1045 upstream. __ptrace_may_access() checks get_dumpable/ptrace_has_cap/etc if task != current, this can can lead to surprising results. For example, a sub-thread can't readlink("/proc/self/exe") if the executable is not readable. setup_new_exec()->would_dump() notices that inode_permission(MAY_READ) fails and then it does set_dumpable(suid_dumpable). After that get_dumpable() fails. (It is not clear why proc_pid_readlink() checks get_dumpable(), perhaps we could add PTRACE_MODE_NODUMPABLE) Change __ptrace_may_access() to use same_thread_group() instead of "task == current". Any security check is pointless when the tasks share the same ->mm. Signed-off-by: Mark Grondona <mgrondona@llnl.gov> Signed-off-by: Ben Woodard <woodard@redhat.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Sheng Yong <shengyong1@huawei.com>
* tracing: Have filter check for balanced opsSteven Rostedt2015-08-071-2/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 2cf30dc180cea808077f003c5116388183e54f9e upstream. When the following filter is used it causes a warning to trigger: # cd /sys/kernel/debug/tracing # echo "((dev==1)blocks==2)" > events/ext4/ext4_truncate_exit/filter -bash: echo: write error: Invalid argument # cat events/ext4/ext4_truncate_exit/filter ((dev==1)blocks==2) ^ parse_error: No error ------------[ cut here ]------------ WARNING: CPU: 2 PID: 1223 at kernel/trace/trace_events_filter.c:1640 replace_preds+0x3c5/0x990() Modules linked in: bnep lockd grace bluetooth ... CPU: 3 PID: 1223 Comm: bash Tainted: G W 4.1.0-rc3-test+ #450 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012 0000000000000668 ffff8800c106bc98 ffffffff816ed4f9 ffff88011ead0cf0 0000000000000000 ffff8800c106bcd8 ffffffff8107fb07 ffffffff8136b46c ffff8800c7d81d48 ffff8800d4c2bc00 ffff8800d4d4f920 00000000ffffffea Call Trace: [<ffffffff816ed4f9>] dump_stack+0x4c/0x6e [<ffffffff8107fb07>] warn_slowpath_common+0x97/0xe0 [<ffffffff8136b46c>] ? _kstrtoull+0x2c/0x80 [<ffffffff8107fb6a>] warn_slowpath_null+0x1a/0x20 [<ffffffff81159065>] replace_preds+0x3c5/0x990 [<ffffffff811596b2>] create_filter+0x82/0xb0 [<ffffffff81159944>] apply_event_filter+0xd4/0x180 [<ffffffff81152bbf>] event_filter_write+0x8f/0x120 [<ffffffff811db2a8>] __vfs_write+0x28/0xe0 [<ffffffff811dda43>] ? __sb_start_write+0x53/0xf0 [<ffffffff812e51e0>] ? security_file_permission+0x30/0xc0 [<ffffffff811dc408>] vfs_write+0xb8/0x1b0 [<ffffffff811dc72f>] SyS_write+0x4f/0xb0 [<ffffffff816f5217>] system_call_fastpath+0x12/0x6a ---[ end trace e11028bd95818dcd ]--- Worse yet, reading the error message (the filter again) it says that there was no error, when there clearly was. The issue is that the code that checks the input does not check for balanced ops. That is, having an op between a closed parenthesis and the next token. This would only cause a warning, and fail out before doing any real harm, but it should still not caues a warning, and the error reported should work: # cd /sys/kernel/debug/tracing # echo "((dev==1)blocks==2)" > events/ext4/ext4_truncate_exit/filter -bash: echo: write error: Invalid argument # cat events/ext4/ext4_truncate_exit/filter ((dev==1)blocks==2) ^ parse_error: Meaningless filter expression And give no kernel warning. Link: http://lkml.kernel.org/r/20150615175025.7e809215@gandalf.local.home Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Reported-by: Vince Weaver <vincent.weaver@maine.edu> Tested-by: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> [bwh: Backported to 3.2: drop the check for OP_NOT, which we don't have] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* ring-buffer-benchmark: Fix the wrong sched_priority of producerWang Long2015-08-071-1/+1
| | | | | | | | | | | | | commit 108029323910c5dd1ef8fa2d10da1ce5fbce6e12 upstream. The producer should be used producer_fifo as its sched_priority, so correct it. Link: http://lkml.kernel.org/r/1433923957-67842-1-git-send-email-long.wanglong@huawei.com Signed-off-by: Wang Long <long.wanglong@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* ptrace: fix race between ptrace_resume() and wait_task_stopped()Oleg Nesterov2015-08-071-0/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit b72c186999e689cb0b055ab1c7b3cd8fffbeb5ed upstream. ptrace_resume() is called when the tracee is still __TASK_TRACED. We set tracee->exit_code and then wake_up_state() changes tracee->state. If the tracer's sub-thread does wait() in between, task_stopped_code(ptrace => T) wrongly looks like another report from tracee. This confuses debugger, and since wait_task_stopped() clears ->exit_code the tracee can miss a signal. Test-case: #include <stdio.h> #include <unistd.h> #include <sys/wait.h> #include <sys/ptrace.h> #include <pthread.h> #include <assert.h> int pid; void *waiter(void *arg) { int stat; for (;;) { assert(pid == wait(&stat)); assert(WIFSTOPPED(stat)); if (WSTOPSIG(stat) == SIGHUP) continue; assert(WSTOPSIG(stat) == SIGCONT); printf("ERR! extra/wrong report:%x\n", stat); } } int main(void) { pthread_t thread; pid = fork(); if (!pid) { assert(ptrace(PTRACE_TRACEME, 0,0,0) == 0); for (;;) kill(getpid(), SIGHUP); } assert(pthread_create(&thread, NULL, waiter, NULL) == 0); for (;;) ptrace(PTRACE_CONT, pid, 0, SIGCONT); return 0; } Note for stable: the bug is very old, but without 9899d11f6544 "ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL" the fix should use lock_task_sighand(child). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Pavel Labath <labath@google.com> Tested-by: Pavel Labath <labath@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* sched: Fix RLIMIT_RTTIME when PI-boosting to RTBrian Silverman2015-05-091-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 746db9443ea57fd9c059f62c4bfbf41cf224fe13 upstream. When non-realtime tasks get priority-inheritance boosted to a realtime scheduling class, RLIMIT_RTTIME starts to apply to them. However, the counter used for checking this (the same one used for SCHED_RR timeslices) was not getting reset. This meant that tasks running with a non-realtime scheduling class which are repeatedly boosted to a realtime one, but never block while they are running realtime, eventually hit the timeout without ever running for a time over the limit. This patch resets the realtime timeslice counter when un-PI-boosting from an RT to a non-RT scheduling class. I have some test code with two threads and a shared PTHREAD_PRIO_INHERIT mutex which induces priority boosting and spins while boosted that gets killed by a SIGXCPU on non-fixed kernels but doesn't with this patch applied. It happens much faster with a CONFIG_PREEMPT_RT kernel, and does happen eventually with PREEMPT_VOLUNTARY kernels. Signed-off-by: Brian Silverman <brian@peloton-tech.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: austin@peloton-tech.com Link: http://lkml.kernel.org/r/1424305436-6716-1-git-send-email-brian@peloton-tech.com Signed-off-by: Ingo Molnar <mingo@kernel.org> [bwh: Backported to 3.2: adjust filename, context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* perf: Fix irq_work 'tail' recursionPeter Zijlstra2015-05-091-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit d525211f9d1be8b523ec7633f080f2116f5ea536 upstream. Vince reported a watchdog lockup like: [<ffffffff8115e114>] perf_tp_event+0xc4/0x210 [<ffffffff810b4f8a>] perf_trace_lock+0x12a/0x160 [<ffffffff810b7f10>] lock_release+0x130/0x260 [<ffffffff816c7474>] _raw_spin_unlock_irqrestore+0x24/0x40 [<ffffffff8107bb4d>] do_send_sig_info+0x5d/0x80 [<ffffffff811f69df>] send_sigio_to_task+0x12f/0x1a0 [<ffffffff811f71ce>] send_sigio+0xae/0x100 [<ffffffff811f72b7>] kill_fasync+0x97/0xf0 [<ffffffff8115d0b4>] perf_event_wakeup+0xd4/0xf0 [<ffffffff8115d103>] perf_pending_event+0x33/0x60 [<ffffffff8114e3fc>] irq_work_run_list+0x4c/0x80 [<ffffffff8114e448>] irq_work_run+0x18/0x40 [<ffffffff810196af>] smp_trace_irq_work_interrupt+0x3f/0xc0 [<ffffffff816c99bd>] trace_irq_work_interrupt+0x6d/0x80 Which is caused by an irq_work generating new irq_work and therefore not allowing forward progress. This happens because processing the perf irq_work triggers another perf event (tracepoint stuff) which in turn generates an irq_work ad infinitum. Avoid this by raising the recursion counter in the irq_work -- which effectively disables all software events (including tracepoints) from actually triggering again. Reported-by: Vince Weaver <vincent.weaver@maine.edu> Tested-by: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20150219170311.GH21418@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* ftrace: Fix ftrace enable ordering of sysctl ftrace_enabledSteven Rostedt (Red Hat)2015-05-091-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 524a38682573b2e15ab6317ccfe50280441514be upstream. Some archs (specifically PowerPC), are sensitive with the ordering of the enabling of the calls to function tracing and setting of the function to use to be traced. That is, update_ftrace_function() sets what function the ftrace_caller trampoline should call. Some archs require this to be set before calling ftrace_run_update_code(). Another bug was discovered, that ftrace_startup_sysctl() called ftrace_run_update_code() directly. If the function the ftrace_caller trampoline changes, then it will not be updated. Instead a call to ftrace_startup_enable() should be called because it tests to see if the callback changed since the code was disabled, and will tell the arch to update appropriately. Most archs do not need this notification, but PowerPC does. The problem could be seen by the following commands: # echo 0 > /proc/sys/kernel/ftrace_enabled # echo function > /sys/kernel/debug/tracing/current_tracer # echo 1 > /proc/sys/kernel/ftrace_enabled # cat /sys/kernel/debug/tracing/trace The trace will show that function tracing was not active. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* ftrace: Fix en(dis)able graph caller when en(dis)abling record via sysctlPratyush Anand2015-05-091-5/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 1619dc3f8f555ee1cdd3c75db3885d5715442b12 upstream. When ftrace is enabled globally through the proc interface, we must check if ftrace_graph_active is set. If it is set, then we should also pass the FTRACE_START_FUNC_RET command to ftrace_run_update_code(). Similarly, when ftrace is disabled globally through the proc interface, we must check if ftrace_graph_active is set. If it is set, then we should also pass the FTRACE_STOP_FUNC_RET command to ftrace_run_update_code(). Consider the following situation. # echo 0 > /proc/sys/kernel/ftrace_enabled After this ftrace_enabled = 0. # echo function_graph > /sys/kernel/debug/tracing/current_tracer Since ftrace_enabled = 0, ftrace_enable_ftrace_graph_caller() is never called. # echo 1 > /proc/sys/kernel/ftrace_enabled Now ftrace_enabled will be set to true, but still ftrace_enable_ftrace_graph_caller() will not be called, which is not desired. Further if we execute the following after this: # echo nop > /sys/kernel/debug/tracing/current_tracer Now since ftrace_enabled is set it will call ftrace_disable_ftrace_graph_caller(), which causes a kernel warning on the ARM platform. On the ARM platform, when ftrace_enable_ftrace_graph_caller() is called, it checks whether the old instruction is a nop or not. If it's not a nop, then it returns an error. If it is a nop then it replaces instruction at that address with a branch to ftrace_graph_caller. ftrace_disable_ftrace_graph_caller() behaves just the opposite. Therefore, if generic ftrace code ever calls either ftrace_enable_ftrace_graph_caller() or ftrace_disable_ftrace_graph_caller() consecutively two times in a row, then it will return an error, which will cause the generic ftrace code to raise a warning. Note, x86 does not have an issue with this because the architecture specific code for ftrace_enable_ftrace_graph_caller() and ftrace_disable_ftrace_graph_caller() does not check the previous state, and calling either of these functions twice in a row has no ill effect. Link: http://lkml.kernel.org/r/e4fbe64cdac0dd0e86a3bf914b0f83c0b419f146.1425666454.git.panand@redhat.com Signed-off-by: Pratyush Anand <panand@redhat.com> [ removed extra if (ftrace_start_up) and defined ftrace_graph_active as 0 if CONFIG_FUNCTION_GRAPH_TRACER is not set. ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* console: Fix console name size mismatchPeter Hurley2015-05-091-1/+2
| | | | | | | | | | | | | | | | | commit 30a22c215a0007603ffc08021f2e8b64018517dd upstream. commit 6ae9200f2cab7 ("enlarge console.name") increased the storage for the console name to 16 bytes, but not the corresponding struct console_cmdline::name storage. Console names longer than 8 bytes cause read beyond end-of-string and failure to match console; I'm not sure if there are other unexpected consequences. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [bwh: Backported to 3.2: - Adjust filename - Use console_cmdline[i] instead of *c] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* kdb: fix incorrect counts in KDB summary command outputJay Lan2015-05-091-1/+1
| | | | | | | | | | | | | | | | | commit 146755923262037fc4c54abc28c04b1103f3cc51 upstream. The output of KDB 'summary' command should report MemTotal, MemFree and Buffers output in kB. Current codes report in unit of pages. A define of K(x) as is defined in the code, but not used. This patch would apply the define to convert the values to kB. Please include me on Cc on replies. I do not subscribe to linux-kernel. Signed-off-by: Jay Lan <jlan@sgi.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* sched/autogroup: Fix failure to set cpu.rt_runtime_usPeter Zijlstra2015-05-092-5/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 1fe89e1b6d270aa0d3452c60d38461ea589594e3 upstream. Because task_group() uses a cache of autogroup_task_group(), whose output depends on sched_class, switching classes can generate problems. In particular, when started as fair, the cache points to the autogroup, so when switching to RT the tg_rt_schedulable() test fails for every cpu.rt_{runtime,period}_us change because now the autogroup has tasks and no runtime. Furthermore, going back to the previous semantics of varying task_group() with sched_class has the down-side that the sched_debug output varies as well, even though the task really is in the autogroup. Therefore add an autogroup exception to tg_has_rt_tasks() -- such that both (all) task_group() usages in sched/core now have one. And remove all the remnants of the variable task_group() output. Reported-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Stefan Bader <stefan.bader@canonical.com> Fixes: 8323f26ce342 ("sched: Fix race in task_group()") Link: http://lkml.kernel.org/r/20150209112237.GR5029@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org> [bwh: Backported to 3.2: adjust filenames, context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* ntp: Fixup adjtimex freq validation on 32-bit systemsJohn Stultz2015-03-061-3/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 29183a70b0b828500816bd794b3fe192fce89f73 upstream. Additional validation of adjtimex freq values to avoid potential multiplication overflows were added in commit 5e5aeb4367b (time: adjtimex: Validate the ADJ_FREQUENCY values) Unfortunately the patch used LONG_MAX/MIN instead of LLONG_MAX/MIN, which was fine on 64-bit systems, but being much smaller on 32-bit systems caused false positives resulting in most direct frequency adjustments to fail w/ EINVAL. ntpd only does direct frequency adjustments at startup, so the issue was not as easily observed there, but other time sync applications like ptpd and chrony were more effected by the bug. See bugs: https://bugzilla.kernel.org/show_bug.cgi?id=92481 https://bugzilla.redhat.com/show_bug.cgi?id=1188074 This patch changes the checks to use LLONG_MAX for clarity, and additionally the checks are disabled on 32-bit systems since LLONG_MAX/PPM_SCALE is always larger then the 32-bit long freq value, so multiplication overflows aren't possible there. Reported-by: Josh Boyer <jwboyer@fedoraproject.org> Reported-by: George Joseph <george.joseph@fairview5.com> Tested-by: George Joseph <george.joseph@fairview5.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Sasha Levin <sasha.levin@oracle.com> Link: http://lkml.kernel.org/r/1423553436-29747-1-git-send-email-john.stultz@linaro.org [ Prettified the changelog and the comments a bit. ] Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* time: adjtimex: Validate the ADJ_FREQUENCY valuesSasha Levin2015-03-061-0/+7
| | | | | | | | | | | | | | | | commit 5e5aeb4367b450a28f447f6d5ab57d8f2ab16a5f upstream. Verify that the frequency value from userspace is valid and makes sense. Unverified values can cause overflows later on. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> [jstultz: Fix up bug for negative values and drop redunent cap check] Signed-off-by: John Stultz <john.stultz@linaro.org> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* sched/rt: Reduce rq lock contention by eliminating locking of non-feasible ↵Tim Chen2015-03-061-1/+16
| | | | | | | | | | | | | | | | | | | | | | | | target commit 80e3d87b2c5582db0ab5e39610ce3707d97ba409 upstream. This patch adds checks that prevens futile attempts to move rt tasks to a CPU with active tasks of equal or higher priority. This reduces run queue lock contention and improves the performance of a well known OLTP benchmark by 0.7%. Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Shawn Bohrer <sbohrer@rgmadvisors.com> Cc: Suruchi Kadu <suruchi.a.kadu@intel.com> Cc: Doug Nelson<doug.nelson@intel.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1421430374.2399.27.camel@schen9-desk2.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* time: settimeofday: Validate the values of tv from userSasha Levin2015-02-201-0/+4
| | | | | | | | | | | | | | | | | commit 6ada1fc0e1c4775de0e043e1bd3ae9d065491aa5 upstream. An unvalidated user input is multiplied by a constant, which can result in an undefined behaviour for large values. While this is validated later, we should avoid triggering undefined behaviour. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> [jstultz: include trivial milisecond->microsecond correction noticed by Andy] Signed-off-by: John Stultz <john.stultz@linaro.org> [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* genirq: Prevent proc race against freeing of irq descriptorsThomas Gleixner2015-02-203-1/+80
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit c291ee622165cb2c8d4e7af63fffd499354a23be upstream. Since the rework of the sparse interrupt code to actually free the unused interrupt descriptors there exists a race between the /proc interfaces to the irq subsystem and the code which frees the interrupt descriptor. CPU0 CPU1 show_interrupts() desc = irq_to_desc(X); free_desc(desc) remove_from_radix_tree(); kfree(desc); raw_spinlock_irq(&desc->lock); /proc/interrupts is the only interface which can actively corrupt kernel memory via the lock access. /proc/stat can only read from freed memory. Extremly hard to trigger, but possible. The interfaces in /proc/irq/N/ are not affected by this because the removal of the proc file is serialized in procfs against concurrent readers/writers. The removal happens before the descriptor is freed. For architectures which have CONFIG_SPARSE_IRQ=n this is a non issue as the descriptor is never freed. It's merely cleared out with the irq descriptor lock held. So any concurrent proc access will either see the old correct value or the cleared out ones. Protect the lookup and access to the irq descriptor in show_interrupts() with the sparse_irq_lock. Provide kstat_irqs_usr() which is protecting the lookup and access with sparse_irq_lock and switch /proc/stat to use it. Document the existing kstat_irqs interfaces so it's clear that the caller needs to take care about protection. The users of these interfaces are either not affected due to SPARSE_IRQ=n or already protected against removal. Fixes: 1f5a5b87f78f "genirq: Implement a sane sparse_irq allocator" Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.2: - Adjust context - Handle the CONFIG_GENERIC_HARDIRQS=n case] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* move d_rcu from overlapping d_child to overlapping d_aliasAl Viro2015-01-011-2/+2
| | | | | | | | | | commit 946e51f2bf37f1656916eb75bd0742ba33983c28 upstream. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> [bwh: Backported to 3.2: - Apply name changes in all the different places we use d_alias and d_child - Move the WARN_ON() in __d_free() to d_free() as we don't have dentry_free()] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* perf: Handle compat ioctlPawel Moll2014-12-141-1/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | commit b3f207855f57b9c8f43a547a801340bb5cbc59e5 upstream. When running a 32-bit userspace on a 64-bit kernel (eg. i386 application on x86_64 kernel or 32-bit arm userspace on arm64 kernel) some of the perf ioctls must be treated with special care, as they have a pointer size encoded in the command. For example, PERF_EVENT_IOC_ID in 32-bit world will be encoded as 0x80042407, but 64-bit kernel will expect 0x80082407. In result the ioctl will fail returning -ENOTTY. This patch solves the problem by adding code fixing up the size as compat_ioctl file operation. Reported-by: Drew Richardson <drew.richardson@arm.com> Signed-off-by: Pawel Moll <pawel.moll@arm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Link: http://lkml.kernel.org/r/1402671812-9078-1-git-send-email-pawel.moll@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: David Ahern <dsahern@gmail.com> [lizf: Backported to 3.4 by David Ahern] Signed-off-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* audit: keep inode pinnedMiklos Szeredi2014-12-141-0/+1
| | | | | | | | | | | | | | | | | | commit 799b601451b21ebe7af0e6e8f6e2ccd4683c5064 upstream. Audit rules disappear when an inode they watch is evicted from the cache. This is likely not what we want. The guilty commit is "fsnotify: allow marks to not pin inodes in core", which didn't take into account that audit_tree adds watches with a zero mask. Adding any mask should fix this. Fixes: 90b1e7a57880 ("fsnotify: allow marks to not pin inodes in core") Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Paul Moore <pmoore@redhat.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* tracing/syscalls: Ignore numbers outside NR_syscalls' rangeRabin Vincent2014-12-141-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 086ba77a6db00ed858ff07451bedee197df868c9 upstream. ARM has some private syscalls (for example, set_tls(2)) which lie outside the range of NR_syscalls. If any of these are called while syscall tracing is being performed, out-of-bounds array access will occur in the ftrace and perf sys_{enter,exit} handlers. # trace-cmd record -e raw_syscalls:* true && trace-cmd report ... true-653 [000] 384.675777: sys_enter: NR 192 (0, 1000, 3, 4000022, ffffffff, 0) true-653 [000] 384.675812: sys_exit: NR 192 = 1995915264 true-653 [000] 384.675971: sys_enter: NR 983045 (76f74480, 76f74000, 76f74b28, 76f74480, 76f76f74, 1) true-653 [000] 384.675988: sys_exit: NR 983045 = 0 ... # trace-cmd record -e syscalls:* true [ 17.289329] Unable to handle kernel paging request at virtual address aaaaaace [ 17.289590] pgd = 9e71c000 [ 17.289696] [aaaaaace] *pgd=00000000 [ 17.289985] Internal error: Oops: 5 [#1] PREEMPT SMP ARM [ 17.290169] Modules linked in: [ 17.290391] CPU: 0 PID: 704 Comm: true Not tainted 3.18.0-rc2+ #21 [ 17.290585] task: 9f4dab00 ti: 9e710000 task.ti: 9e710000 [ 17.290747] PC is at ftrace_syscall_enter+0x48/0x1f8 [ 17.290866] LR is at syscall_trace_enter+0x124/0x184 Fix this by ignoring out-of-NR_syscalls-bounds syscall numbers. Commit cd0980fc8add "tracing: Check invalid syscall nr while tracing syscalls" added the check for less than zero, but it should have also checked for greater than NR_syscalls. Link: http://lkml.kernel.org/p/1414620418-29472-1-git-send-email-rabin@rab.in Fixes: cd0980fc8add "tracing: Check invalid syscall nr while tracing syscalls" Signed-off-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* tracing/syscalls: Fix perf syscall tracing when syscall_nr == -1Will Deacon2014-12-141-0/+4
| | | | | | | | | | | | | | | | | | | commit 60916a9382e88fbf5e54fd36a3e658efd7ab7bed upstream. syscall_get_nr can return -1 in the case that the task is not executing a system call. This patch fixes perf_syscall_{enter,exit} to check that the syscall number is valid before using it as an index into a bitmap. Link: http://lkml.kernel.org/r/1345137254-7377-1-git-send-email-will.deacon@arm.com Cc: Jason Baron <jbaron@redhat.com> Cc: Wade Farnsworth <wade_farnsworth@mentor.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* PM / Sleep: fix recovery during resuming from hibernationImre Deak2014-12-141-1/+7
| | | | | | | | | | | | | commit 94fb823fcb4892614f57e59601bb9d4920f24711 upstream. If a device's dev_pm_ops::freeze callback fails during the QUIESCE phase, we don't rollback things correctly calling the thaw and complete callbacks. This could leave some devices in a suspended state in case of an error during resuming from hibernation. Signed-off-by: Imre Deak <imre.deak@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* futex: Fix a race condition between REQUEUE_PI and task deathBrian Silverman2014-12-141-11/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 30a6b8031fe14031ab27c1fa3483cb9780e7f63c upstream. free_pi_state and exit_pi_state_list both clean up futex_pi_state's. exit_pi_state_list takes the hb lock first, and most callers of free_pi_state do too. requeue_pi doesn't, which means free_pi_state can free the pi_state out from under exit_pi_state_list. For example: task A | task B exit_pi_state_list | pi_state = | curr->pi_state_list->next | | futex_requeue(requeue_pi=1) | // pi_state is the same as | // the one in task A | free_pi_state(pi_state) | list_del_init(&pi_state->list) | kfree(pi_state) list_del_init(&pi_state->list) | Move the free_pi_state calls in requeue_pi to before it drops the hb locks which it's already holding. [ tglx: Removed a pointless free_pi_state() call and the hb->lock held debugging. The latter comes via a seperate patch ] Signed-off-by: Brian Silverman <bsilver16384@gmail.com> Cc: austin.linux@gmail.com Cc: darren@dvhart.com Cc: peterz@infradead.org Link: http://lkml.kernel.org/r/1414282837-23092-1-git-send-email-bsilver16384@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* posix-timers: Fix stack info leak in timer_create()Mathias Krause2014-12-141-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | commit 6891c4509c792209c44ced55a60f13954cb50ef4 upstream. If userland creates a timer without specifying a sigevent info, we'll create one ourself, using a stack local variable. Particularly will we use the timer ID as sival_int. But as sigev_value is a union containing a pointer and an int, that assignment will only partially initialize sigev_value on systems where the size of a pointer is bigger than the size of an int. On such systems we'll copy the uninitialized stack bytes from the timer_create() call to userland when the timer actually fires and we're going to deliver the signal. Initialize sigev_value with 0 to plug the stack info leak. Found in the PaX patch, written by the PaX Team. Fixes: 5a9fa7307285 ("posix-timers: kill ->it_sigev_signo and...") Signed-off-by: Mathias Krause <minipli@googlemail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Brad Spengler <spender@grsecurity.net> Cc: PaX Team <pageexec@freemail.hu> Link: http://lkml.kernel.org/r/1412456799-32339-1-git-send-email-minipli@googlemail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* ring-buffer: Fix infinite spin in reading bufferSteven Rostedt (Red Hat)2014-11-051-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 24607f114fd14f2f37e3e0cb3d47bce96e81e848 upstream. Commit 651e22f2701b "ring-buffer: Always reset iterator to reader page" fixed one bug but in the process caused another one. The reset is to update the header page, but that fix also changed the way the cached reads were updated. The cache reads are used to test if an iterator needs to be updated or not. A ring buffer iterator, when created, disables writes to the ring buffer but does not stop other readers or consuming reads from happening. Although all readers are synchronized via a lock, they are only synchronized when in the ring buffer functions. Those functions may be called by any number of readers. The iterator continues down when its not interrupted by a consuming reader. If a consuming read occurs, the iterator starts from the beginning of the buffer. The way the iterator sees that a consuming read has happened since its last read is by checking the reader "cache". The cache holds the last counts of the read and the reader page itself. Commit 651e22f2701b changed what was saved by the cache_read when the rb_iter_reset() occurred, making the iterator never match the cache. Then if the iterator calls rb_iter_reset(), it will go into an infinite loop by checking if the cache doesn't match, doing the reset and retrying, just to see that the cache still doesn't match! Which should never happen as the reset is suppose to set the cache to the current value and there's locks that keep a consuming reader from having access to the data. Fixes: 651e22f2701b "ring-buffer: Always reset iterator to reader page" Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* perf: fix perf bug in fork()Peter Zijlstra2014-11-052-3/+6
| | | | | | | | | | | | | | | | | | | commit 6c72e3501d0d62fc064d3680e5234f3463ec5a86 upstream. Oleg noticed that a cleanup by Sylvain actually uncovered a bug; by calling perf_event_free_task() when failing sched_fork() we will not yet have done the memset() on ->perf_event_ctxp[] and will therefore try and 'free' the inherited contexts, which are still in use by the parent process. This is bad.. Suggested-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Sylvain 'ythier' Hitier <sylvain.hitier@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* alarmtimer: Lock k_itimer during timer callbackRichard Larocque2014-11-051-2/+8
| | | | | | | | | | | | | | | | | | | | | commit 474e941bed9262f5fa2394f9a4a67e24499e5926 upstream. Locks the k_itimer's it_lock member when handling the alarm timer's expiry callback. The regular posix timers defined in posix-timers.c have this lock held during timout processing because their callbacks are routed through posix_timer_fn(). The alarm timers follow a different path, so they ought to grab the lock somewhere else. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Sharvil Nanavati <sharvil@google.com> Signed-off-by: Richard Larocque <rlarocque@google.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* alarmtimer: Do not signal SIGEV_NONE timersRichard Larocque2014-11-051-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 265b81d23a46c39df0a735a3af4238954b41a4c2 upstream. Avoids sending a signal to alarm timers created with sigev_notify set to SIGEV_NONE by checking for that special case in the timeout callback. The regular posix timers avoid sending signals to SIGEV_NONE timers by not scheduling any callbacks for them in the first place. Although it would be possible to do something similar for alarm timers, it's simpler to handle this as a special case in the timeout. Prior to this patch, the alarm timer would ignore the sigev_notify value and try to deliver signals to the process anyway. Even worse, the sanity check for the value of sigev_signo is skipped when SIGEV_NONE was specified, so the signal number could be bogus. If sigev_signo was an unitialized value (as it often would be if SIGEV_NONE is used), then it's hard to predict which signal will be sent. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Sharvil Nanavati <sharvil@google.com> Signed-off-by: Richard Larocque <rlarocque@google.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* alarmtimer: Return relative times in timer_gettimeRichard Larocque2014-11-051-7/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | commit e86fea764991e00a03ff1e56409ec9cacdbda4c9 upstream. Returns the time remaining for an alarm timer, rather than the time at which it is scheduled to expire. If the timer has already expired or it is not currently scheduled, the it_value's members are set to zero. This new behavior matches that of the other posix-timers and the POSIX specifications. This is a change in user-visible behavior, and may break existing applications. Hopefully, few users rely on the old incorrect behavior. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Sharvil Nanavati <sharvil@google.com> Signed-off-by: Richard Larocque <rlarocque@google.com> [jstultz: minor style tweak] Signed-off-by: John Stultz <john.stultz@linaro.org> [bwh: Backported to 3.2: Add definition of alarm_expires_remaining() from commit 6cffe00f7d4e ('alarmtimer: Add functions for timerfd support')] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* jiffies: Fix timeval conversion to jiffiesAndrew Hunter2014-11-051-24/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit d78c9300c51d6ceed9f6d078d4e9366f259de28c upstream. timeval_to_jiffies tried to round a timeval up to an integral number of jiffies, but the logic for doing so was incorrect: intervals corresponding to exactly N jiffies would become N+1. This manifested itself particularly repeatedly stopping/starting an itimer: setitimer(ITIMER_PROF, &val, NULL); setitimer(ITIMER_PROF, NULL, &val); would add a full tick to val, _even if it was exactly representable in terms of jiffies_ (say, the result of a previous rounding.) Doing this repeatedly would cause unbounded growth in val. So fix the math. Here's what was wrong with the conversion: we essentially computed (eliding seconds) jiffies = usec * (NSEC_PER_USEC/TICK_NSEC) by using scaling arithmetic, which took the best approximation of NSEC_PER_USEC/TICK_NSEC with denominator of 2^USEC_JIFFIE_SC = x/(2^USEC_JIFFIE_SC), and computed: jiffies = (usec * x) >> USEC_JIFFIE_SC and rounded this calculation up in the intermediate form (since we can't necessarily exactly represent TICK_NSEC in usec.) But the scaling arithmetic is a (very slight) *over*approximation of the true value; that is, instead of dividing by (1 usec/ 1 jiffie), we effectively divided by (1 usec/1 jiffie)-epsilon (rounding down). This would normally be fine, but we want to round timeouts up, and we did so by adding 2^USEC_JIFFIE_SC - 1 before the shift; this would be fine if our division was exact, but dividing this by the slightly smaller factor was equivalent to adding just _over_ 1 to the final result (instead of just _under_ 1, as desired.) In particular, with HZ=1000, we consistently computed that 10000 usec was 11 jiffies; the same was true for any exact multiple of TICK_NSEC. We could possibly still round in the intermediate form, adding something less than 2^USEC_JIFFIE_SC - 1, but easier still is to convert usec->nsec, round in nanoseconds, and then convert using time*spec*_to_jiffies. This adds one constant multiplication, and is not observably slower in microbenchmarks on recent x86 hardware. Tested: the following program: int main() { struct itimerval zero = {{0, 0}, {0, 0}}; /* Initially set to 10 ms. */ struct itimerval initial = zero; initial.it_interval.tv_usec = 10000; setitimer(ITIMER_PROF, &initial, NULL); /* Save and restore several times. */ for (size_t i = 0; i < 10; ++i) { struct itimerval prev; setitimer(ITIMER_PROF, &zero, &prev); /* on old kernels, this goes up by TICK_USEC every iteration */ printf("previous value: %ld %ld %ld %ld\n", prev.it_interval.tv_sec, prev.it_interval.tv_usec, prev.it_value.tv_sec, prev.it_value.tv_usec); setitimer(ITIMER_PROF, &prev, NULL); } return 0; } Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Paul Turner <pjt@google.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Reviewed-by: Paul Turner <pjt@google.com> Reported-by: Aaron Jacobs <jacobsa@google.com> Signed-off-by: Andrew Hunter <ahh@google.com> [jstultz: Tweaked to apply to 3.17-rc] Signed-off-by: John Stultz <john.stultz@linaro.org> [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* futex: Unlock hb->lock in futex_wait_requeue_pi() error pathThomas Gleixner2014-11-051-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 13c42c2f43b19aab3195f2d357db00d1e885eaa8 upstream. futex_wait_requeue_pi() calls futex_wait_setup(). If futex_wait_setup() succeeds it returns with hb->lock held and preemption disabled. Now the sanity check after this does: if (match_futex(&q.key, &key2)) { ret = -EINVAL; goto out_put_keys; } which releases the keys but does not release hb->lock. So we happily return to user space with hb->lock held and therefor preemption disabled. Unlock hb->lock before taking the exit route. Reported-by: Dave "Trinity" Jones <davej@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Darren Hart <dvhart@linux.intel.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1409112318500.4178@nanos Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.2: queue_unlock() takes two parameters] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* perf: Fix a race condition in perf_remove_from_context()Cong Wang2014-11-051-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 3577af70a2ce4853d58e57d832e687d739281479 upstream. We saw a kernel soft lockup in perf_remove_from_context(), it looks like the `perf` process, when exiting, could not go out of the retry loop. Meanwhile, the target process was forking a child. So either the target process should execute the smp function call to deactive the event (if it was running) or it should do a context switch which deactives the event. It seems we optimize out a context switch in perf_event_context_sched_out(), and what's more important, we still test an obsolete task pointer when retrying, so no one actually would deactive that event in this situation. Fix it directly by reloading the task pointer in perf_remove_from_context(). This should cure the above soft lockup. Signed-off-by: Cong Wang <cwang@twopensource.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1409696840-843-1-git-send-email-xiyou.wangcong@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* cgroup: reject cgroup names with 'Alban Crequy2014-11-051-0/+5
| | | | | | | | | | | | | | | | ' commit 71b1fb5c4473a5b1e601d41b109bdfe001ec82e0 upstream. /proc/<pid>/cgroup contains one cgroup path on each line. If cgroup names are allowed to contain "\n", applications cannot parse /proc/<pid>/cgroup safely. Signed-off-by: Alban Crequy <alban.crequy@collabora.co.uk> Signed-off-by: Tejun Heo <tj@kernel.org> [bwh: Backported to 3.2: - Adjust context - We have to get the name from the dentry pointer] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* ring-buffer: Always reset iterator to reader pageSteven Rostedt (Red Hat)2014-09-131-11/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 651e22f2701b4113989237c3048d17337dd2185c upstream. When performing a consuming read, the ring buffer swaps out a page from the ring buffer with a empty page and this page that was swapped out becomes the new reader page. The reader page is owned by the reader and since it was swapped out of the ring buffer, writers do not have access to it (there's an exception to that rule, but it's out of scope for this commit). When reading the "trace" file, it is a non consuming read, which means that the data in the ring buffer will not be modified. When the trace file is opened, a ring buffer iterator is allocated and writes to the ring buffer are disabled, such that the iterator will not have issues iterating over the data. Although the ring buffer disabled writes, it does not disable other reads, or even consuming reads. If a consuming read happens, then the iterator is reset and starts reading from the beginning again. My tests would sometimes trigger this bug on my i386 box: WARNING: CPU: 0 PID: 5175 at kernel/trace/trace.c:1527 __trace_find_cmdline+0x66/0xaa() Modules linked in: CPU: 0 PID: 5175 Comm: grep Not tainted 3.16.0-rc3-test+ #8 Hardware name: /DG965MQ, BIOS MQ96510J.86A.0372.2006.0605.1717 06/05/2006 00000000 00000000 f09c9e1c c18796b3 c1b5d74c f09c9e4c c103a0e3 c1b5154b f09c9e78 00001437 c1b5d74c 000005f7 c10bd85a c10bd85a c1cac57c f09c9eb0 ed0e0000 f09c9e64 c103a185 00000009 f09c9e5c c1b5154b f09c9e78 f09c9e80^M Call Trace: [<c18796b3>] dump_stack+0x4b/0x75 [<c103a0e3>] warn_slowpath_common+0x7e/0x95 [<c10bd85a>] ? __trace_find_cmdline+0x66/0xaa [<c10bd85a>] ? __trace_find_cmdline+0x66/0xaa [<c103a185>] warn_slowpath_fmt+0x33/0x35 [<c10bd85a>] __trace_find_cmdline+0x66/0xaa^M [<c10bed04>] trace_find_cmdline+0x40/0x64 [<c10c3c16>] trace_print_context+0x27/0xec [<c10c4360>] ? trace_seq_printf+0x37/0x5b [<c10c0b15>] print_trace_line+0x319/0x39b [<c10ba3fb>] ? ring_buffer_read+0x47/0x50 [<c10c13b1>] s_show+0x192/0x1ab [<c10bfd9a>] ? s_next+0x5a/0x7c [<c112e76e>] seq_read+0x267/0x34c [<c1115a25>] vfs_read+0x8c/0xef [<c112e507>] ? seq_lseek+0x154/0x154 [<c1115ba2>] SyS_read+0x54/0x7f [<c188488e>] syscall_call+0x7/0xb ---[ end trace 3f507febd6b4cc83 ]--- >>>> ##### CPU 1 buffer started #### Which was the __trace_find_cmdline() function complaining about the pid in the event record being negative. After adding more test cases, this would trigger more often. Strangely enough, it would never trigger on a single test, but instead would trigger only when running all the tests. I believe that was the case because it required one of the tests to be shutting down via delayed instances while a new test started up. After spending several days debugging this, I found that it was caused by the iterator becoming corrupted. Debugging further, I found out why the iterator became corrupted. It happened with the rb_iter_reset(). As consuming reads may not read the full reader page, and only part of it, there's a "read" field to know where the last read took place. The iterator, must also start at the read position. In the rb_iter_reset() code, if the reader page was disconnected from the ring buffer, the iterator would start at the head page within the ring buffer (where writes still happen). But the mistake there was that it still used the "read" field to start the iterator on the head page, where it should always start at zero because readers never read from within the ring buffer where writes occur. I originally wrote a patch to have it set the iter->head to 0 instead of iter->head_page->read, but then I questioned why it wasn't always setting the iter to point to the reader page, as the reader page is still valid. The list_empty(reader_page->list) just means that it was successful in swapping out. But the reader_page may still have data. There was a bug report a long time ago that was not reproducible that had something about trace_pipe (consuming read) not matching trace (iterator read). This may explain why that happened. Anyway, the correct answer to this bug is to always use the reader page an not reset the iterator to inside the writable ring buffer. Fixes: d769041f8653 "ring_buffer: implement new locking" Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* ring-buffer: Up rb_iter_peek() loop count to 3Steven Rostedt (Red Hat)2014-09-131-5/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 021de3d904b88b1771a3a2cfc5b75023c391e646 upstream. After writting a test to try to trigger the bug that caused the ring buffer iterator to become corrupted, I hit another bug: WARNING: CPU: 1 PID: 5281 at kernel/trace/ring_buffer.c:3766 rb_iter_peek+0x113/0x238() Modules linked in: ipt_MASQUERADE sunrpc [...] CPU: 1 PID: 5281 Comm: grep Tainted: G W 3.16.0-rc3-test+ #143 Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007 0000000000000000 ffffffff81809a80 ffffffff81503fb0 0000000000000000 ffffffff81040ca1 ffff8800796d6010 ffffffff810c138d ffff8800796d6010 ffff880077438c80 ffff8800796d6010 ffff88007abbe600 0000000000000003 Call Trace: [<ffffffff81503fb0>] ? dump_stack+0x4a/0x75 [<ffffffff81040ca1>] ? warn_slowpath_common+0x7e/0x97 [<ffffffff810c138d>] ? rb_iter_peek+0x113/0x238 [<ffffffff810c138d>] ? rb_iter_peek+0x113/0x238 [<ffffffff810c14df>] ? ring_buffer_iter_peek+0x2d/0x5c [<ffffffff810c6f73>] ? tracing_iter_reset+0x6e/0x96 [<ffffffff810c74a3>] ? s_start+0xd7/0x17b [<ffffffff8112b13e>] ? kmem_cache_alloc_trace+0xda/0xea [<ffffffff8114cf94>] ? seq_read+0x148/0x361 [<ffffffff81132d98>] ? vfs_read+0x93/0xf1 [<ffffffff81132f1b>] ? SyS_read+0x60/0x8e [<ffffffff8150bf9f>] ? tracesys+0xdd/0xe2 Debugging this bug, which triggers when the rb_iter_peek() loops too many times (more than 2 times), I discovered there's a case that can cause that function to legitimately loop 3 times! rb_iter_peek() is different than rb_buffer_peek() as the rb_buffer_peek() only deals with the reader page (it's for consuming reads). The rb_iter_peek() is for traversing the buffer without consuming it, and as such, it can loop for one more reason. That is, if we hit the end of the reader page or any page, it will go to the next page and try again. That is, we have this: 1. iter->head > iter->head_page->page->commit (rb_inc_iter() which moves the iter to the next page) try again 2. event = rb_iter_head_event() event->type_len == RINGBUF_TYPE_TIME_EXTEND rb_advance_iter() try again 3. read the event. But we never get to 3, because the count is greater than 2 and we cause the WARNING and return NULL. Up the counter to 3. Fixes: 69d1b839f7ee "ring-buffer: Bind time extend and data events together" Signed-off-by: Steven Rostedt <rostedt@goodmis.org> [bwh: Backported to 3.2: drop inapplicable spelling correction] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=offThomas Gleixner2014-08-061-1/+3
| | | | | | | | | | | | | | | | | | | commit 0e576acbc1d9600cf2d9b4a141a2554639959d50 upstream. If CONFIG_NO_HZ=n tick_nohz_get_sleep_length() returns NSEC_PER_SEC/HZ. If CONFIG_NO_HZ=y and the nohz functionality is disabled via the command line option "nohz=off" or not enabled due to missing hardware support, then tick_nohz_get_sleep_length() returns 0. That happens because ts->sleep_length is never set in that case. Set it to NSEC_PER_SEC/HZ when the NOHZ mode is inactive. Reported-by: Michal Hocko <mhocko@suse.cz> Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* locking/mutex: Disable optimistic spinning on some architecturesPeter Zijlstra2014-08-061-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 4badad352a6bb202ec68afa7a574c0bb961e5ebc upstream. The optimistic spin code assumes regular stores and cmpxchg() play nice; this is found to not be true for at least: parisc, sparc32, tile32, metag-lock1, arc-!llsc and hexagon. There is further wreckage, but this in particular seemed easy to trigger, so blacklist this. Opt in for known good archs. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Reported-by: Mikulas Patocka <mpatocka@redhat.com> Cc: David Miller <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: James Bottomley <James.Bottomley@hansenpartnership.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Jason Low <jason.low2@hp.com> Cc: Waiman Long <waiman.long@hp.com> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: John David Anglin <dave.anglin@bell.net> Cc: James Hogan <james.hogan@imgtec.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: sparclinux@vger.kernel.org Link: http://lkml.kernel.org/r/20140606175316.GV13930@laptop.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org> [bwh: Backported to 3.2: - Adjust context - Drop arm64 change] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* sched: Fix possible divide by zero in avg_atom() calculationMateusz Guzik2014-08-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | commit b0ab99e7736af88b8ac1b7ae50ea287fffa2badc upstream. proc_sched_show_task() does: if (nr_switches) do_div(avg_atom, nr_switches); nr_switches is unsigned long and do_div truncates it to 32 bits, which means it can test non-zero on e.g. x86-64 and be truncated to zero for division. Fix the problem by using div64_ul() instead. As a side effect calculations of avg_atom for big nr_switches are now correct. Signed-off-by: Mateusz Guzik <mguzik@redhat.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1402750809-31991-1-git-send-email-mguzik@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* ring-buffer: Fix polling on trace_pipeMartin Lau2014-08-061-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 97b8ee845393701edc06e27ccec2876ff9596019 upstream. ring_buffer_poll_wait() should always put the poll_table to its wait_queue even there is immediate data available. Otherwise, the following epoll and read sequence will eventually hang forever: 1. Put some data to make the trace_pipe ring_buffer read ready first 2. epoll_ctl(efd, EPOLL_CTL_ADD, trace_pipe_fd, ee) 3. epoll_wait() 4. read(trace_pipe_fd) till EAGAIN 5. Add some more data to the trace_pipe ring_buffer 6. epoll_wait() -> this epoll_wait() will block forever ~ During the epoll_ctl(efd, EPOLL_CTL_ADD,...) call in step 2, ring_buffer_poll_wait() returns immediately without adding poll_table, which has poll_table->_qproc pointing to ep_poll_callback(), to its wait_queue. ~ During the epoll_wait() call in step 3 and step 6, ring_buffer_poll_wait() cannot add ep_poll_callback() to its wait_queue because the poll_table->_qproc is NULL and it is how epoll works. ~ When there is new data available in step 6, ring_buffer does not know it has to call ep_poll_callback() because it is not in its wait queue. Hence, block forever. Other poll implementation seems to call poll_wait() unconditionally as the very first thing to do. For example, tcp_poll() in tcp.c. Link: http://lkml.kernel.org/p/20140610060637.GA14045@devbig242.prn2.facebook.com Fixes: 2a2cc8f7c4d0 "ftrace: allow the event pipe to be polled" Reviewed-by: Chris Mason <clm@fb.com> Signed-off-by: Martin Lau <kafai@fb.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> [bwh: Backported to 3.2: the poll implementation looks rather different but does have a conditional return before and after the poll_wait() call; delete the return before it.] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* alarmtimer: Fix bug where relative alarm timers were treated as absoluteJohn Stultz2014-08-061-2/+18
| | | | | | | | | | | | | | | | | | | | | | commit 16927776ae757d0d132bdbfabbfe2c498342bd59 upstream. Sharvil noticed with the posix timer_settime interface, using the CLOCK_REALTIME_ALARM or CLOCK_BOOTTIME_ALARM clockid, if the users tried to specify a relative time timer, it would incorrectly be treated as absolute regardless of the state of the flags argument. This patch corrects this, properly checking the absolute/relative flag, as well as adds further error checking that no invalid flag bits are set. Reported-by: Sharvil Nanavati <sharvil@google.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Sharvil Nanavati <sharvil@google.com> Link: http://lkml.kernel.org/r/1404767171-6902-1-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* cpuset,mempolicy: fix sleeping function called from invalid contextGu Zheng2014-08-061-1/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 391acf970d21219a2a5446282d3b20eace0c0d7a upstream. When runing with the kernel(3.15-rc7+), the follow bug occurs: [ 9969.258987] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:586 [ 9969.359906] in_atomic(): 1, irqs_disabled(): 0, pid: 160655, name: python [ 9969.441175] INFO: lockdep is turned off. [ 9969.488184] CPU: 26 PID: 160655 Comm: python Tainted: G A 3.15.0-rc7+ #85 [ 9969.581032] Hardware name: FUJITSU-SV PRIMEQUEST 1800E/SB, BIOS PRIMEQUEST 1000 Series BIOS Version 1.39 11/16/2012 [ 9969.706052] ffffffff81a20e60 ffff8803e941fbd0 ffffffff8162f523 ffff8803e941fd18 [ 9969.795323] ffff8803e941fbe0 ffffffff8109995a ffff8803e941fc58 ffffffff81633e6c [ 9969.884710] ffffffff811ba5dc ffff880405c6b480 ffff88041fdd90a0 0000000000002000 [ 9969.974071] Call Trace: [ 9970.003403] [<ffffffff8162f523>] dump_stack+0x4d/0x66 [ 9970.065074] [<ffffffff8109995a>] __might_sleep+0xfa/0x130 [ 9970.130743] [<ffffffff81633e6c>] mutex_lock_nested+0x3c/0x4f0 [ 9970.200638] [<ffffffff811ba5dc>] ? kmem_cache_alloc+0x1bc/0x210 [ 9970.272610] [<ffffffff81105807>] cpuset_mems_allowed+0x27/0x140 [ 9970.344584] [<ffffffff811b1303>] ? __mpol_dup+0x63/0x150 [ 9970.409282] [<ffffffff811b1385>] __mpol_dup+0xe5/0x150 [ 9970.471897] [<ffffffff811b1303>] ? __mpol_dup+0x63/0x150 [ 9970.536585] [<ffffffff81068c86>] ? copy_process.part.23+0x606/0x1d40 [ 9970.613763] [<ffffffff810bf28d>] ? trace_hardirqs_on+0xd/0x10 [ 9970.683660] [<ffffffff810ddddf>] ? monotonic_to_bootbased+0x2f/0x50 [ 9970.759795] [<ffffffff81068cf0>] copy_process.part.23+0x670/0x1d40 [ 9970.834885] [<ffffffff8106a598>] do_fork+0xd8/0x380 [ 9970.894375] [<ffffffff81110e4c>] ? __audit_syscall_entry+0x9c/0xf0 [ 9970.969470] [<ffffffff8106a8c6>] SyS_clone+0x16/0x20 [ 9971.030011] [<ffffffff81642009>] stub_clone+0x69/0x90 [ 9971.091573] [<ffffffff81641c29>] ? system_call_fastpath+0x16/0x1b The cause is that cpuset_mems_allowed() try to take mutex_lock(&callback_mutex) under the rcu_read_lock(which was hold in __mpol_dup()). And in cpuset_mems_allowed(), the access to cpuset is under rcu_read_lock, so in __mpol_dup, we can reduce the rcu_read_lock protection region to protect the access to cpuset only in current_cpuset_is_being_rebound(). So that we can avoid this bug. This patch is a temporary solution that just addresses the bug mentioned above, can not fix the long-standing issue about cpuset.mems rebinding on fork(): "When the forker's task_struct is duplicated (which includes ->mems_allowed) and it races with an update to cpuset_being_rebound in update_tasks_nodemask() then the task's mems_allowed doesn't get updated. And the child task's mems_allowed can be wrong if the cpuset's nodemask changes before the child has been added to the cgroup's tasklist." Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com> Acked-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
* perf: Fix race in removing an eventPeter Zijlstra2014-07-111-20/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 46ce0fe97a6be7532ce6126bb26ce89fed81528c upstream. When removing a (sibling) event we do: raw_spin_lock_irq(&ctx->lock); perf_group_detach(event); raw_spin_unlock_irq(&ctx->lock); <hole> perf_remove_from_context(event); raw_spin_lock_irq(&ctx->lock); ... raw_spin_unlock_irq(&ctx->lock); Now, assuming the event is a sibling, it will be 'unreachable' for things like ctx_sched_out() because that iterates the groups->siblings, and we just unhooked the sibling. So, if during <hole> we get ctx_sched_out(), it will miss the event and not call event_sched_out() on it, leaving it programmed on the PMU. The subsequent perf_remove_from_context() call will find the ctx is inactive and only call list_del_event() to remove the event from all other lists. Hereafter we can proceed to free the event; while still programmed! Close this hole by moving perf_group_detach() inside the same ctx->lock region(s) perf_remove_from_context() has. The condition on inherited events only in __perf_event_exit_task() is likely complete crap because non-inherited events are part of groups too and we're tearing down just the same. But leave that for another patch. Most-likely-Fixes: e03a9a55b4e ("perf: Change close() semantics for group events") Reported-by: Vince Weaver <vincent.weaver@maine.edu> Tested-by: Vince Weaver <vincent.weaver@maine.edu> Much-staring-at-traces-by: Vince Weaver <vincent.weaver@maine.edu> Much-staring-at-traces-by: Thomas Gleixner <tglx@linutronix.de> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140505093124.GN17778@laptop.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org> [bwh: Backported to 3.2: drop change in perf_pmu_migrate_context()] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
generated by cgit v1.1 at 2024-05-05 00:21:29 +0000